feat(brand): 브랜드 도메인 모델 및 도메인 서비스 구현

- Brand 엔티티 생성 및 도메인 검증 로직 추가
- BrandRepository 인터페이스 정의
- Brand 도메인 서비스 설계
- Brand 단위/통합 테스트 작성 (생성/검증)

Author: adminhelper

apps/commerce-api/src/main/java/com/loopers/domain/brand/Brand.java

@@ -0,0 +1,47 @@
+package com.loopers.domain.brand;
+
+import com.loopers.support.error.CoreException;
+import com.loopers.support.error.ErrorType;
+import jakarta.persistence.*;
+import lombok.Getter;
+
+/**
+ * packageName : com.loopers.domain.brand
+ * fileName     : Brand
+ * author      : byeonsungmun
+ * date        : 2025. 11. 11.
+ * description :
+ * ===========================================
+ * DATE         AUTHOR       NOTE
+ * -------------------------------------------
+ * 2025. 11. 11.     byeonsungmun       최초 생성
+ */
+@Entity
+@Table(name = "brand")
+@Getter
+public class Brand {
+    @Id
+    @GeneratedValue(strategy = GenerationType.IDENTITY)
+    private Long id;
+
+    @Column(nullable = false)
+    private String name;
+
+    protected  Brand() {}
+
+    private Brand(String name) {
+        this.name = requireValidName(name);
+    }
+
+    public static Brand create(String name) {
+        return new Brand(name);
+    }
+
+
+    private String requireValidName(String name) {
+        if (name == null || name.isEmpty()) {
+            throw new CoreException(ErrorType.BAD_REQUEST, "상품명 비어 있을수 없습니다.");
+        }
+        return name.trim();
+    }
+}

apps/commerce-api/src/main/java/com/loopers/domain/brand/BrandRepository.java

@@ -0,0 +1,20 @@
+package com.loopers.domain.brand;
+
+import java.util.Optional;
+
+/**
+ * packageName : com.loopers.domain.brand
+ * fileName     : BrandRepository
+ * author      : byeonsungmun
+ * date        : 2025. 11. 12.
+ * description :
+ * ===========================================
+ * DATE         AUTHOR       NOTE
+ * -------------------------------------------
+ * 2025. 11. 12.     byeonsungmun       최초 생성
+ */
+public interface BrandRepository {
+    Optional<Brand> findById(Long id);
+
+    void save(Brand brand);
+}

apps/commerce-api/src/main/java/com/loopers/domain/brand/BrandService.java

@@ -0,0 +1,36 @@
+package com.loopers.domain.brand;
+
+import com.loopers.support.error.CoreException;
+import com.loopers.support.error.ErrorType;
+import lombok.RequiredArgsConstructor;
+import org.springframework.stereotype.Component;
+import org.springframework.transaction.annotation.Transactional;
+
+/**
+ * packageName : com.loopers.domain.brand
+ * fileName     : BrandService
+ * author      : byeonsungmun
+ * date        : 2025. 11. 12.
+ * description :
+ * ===========================================
+ * DATE         AUTHOR       NOTE
+ * -------------------------------------------
+ * 2025. 11. 12.     byeonsungmun       최초 생성
+ */
+@Component
+@RequiredArgsConstructor
+public class BrandService {
+
+    private final BrandRepository brandRepository;
+
+    @Transactional
+    public void save(Brand brand) {
+        brandRepository.save(brand);
+    }
+
+    @Transactional(readOnly = true)
+    public Brand getBrand(Long id) {
+        return brandRepository.findById(id)
+                .orElseThrow(() -> new CoreException(ErrorType.NOT_FOUND, "브랜드를 찾을 수 없습니다."));
+    }
+}

apps/commerce-api/src/main/java/com/loopers/infrastructure/brand/BrandJpaRepository.java

@@ -0,0 +1,21 @@
+package com.loopers.infrastructure.brand;
+
+import com.loopers.domain.brand.Brand;
+import org.springframework.data.jpa.repository.JpaRepository;
+
+import java.util.Optional;
+
+/**
+ * packageName : com.loopers.infrastructure.brand
+ * fileName     : BrandJpaRepository
+ * author      : byeonsungmun
+ * date        : 2025. 11. 12.
+ * description :
+ * ===========================================
+ * DATE         AUTHOR       NOTE
+ * -------------------------------------------
+ * 2025. 11. 12.     byeonsungmun       최초 생성
+ */
+public interface BrandJpaRepository extends JpaRepository<Brand, Long> {
+    Optional<Brand> findById(Long id);
+}

apps/commerce-api/src/main/java/com/loopers/infrastructure/brand/BrandRepositoryImpl.java

@@ -0,0 +1,36 @@
+package com.loopers.infrastructure.brand;
+
+import com.loopers.domain.brand.Brand;
+import com.loopers.domain.brand.BrandRepository;
+import lombok.RequiredArgsConstructor;
+import org.springframework.stereotype.Component;
+
+import java.util.Optional;
+
+/**
+ * packageName : com.loopers.infrastructure.brand
+ * fileName     : BrandRepositroyImpl
+ * author      : byeonsungmun
+ * date        : 2025. 11. 12.
+ * description :
+ * ===========================================
+ * DATE         AUTHOR       NOTE
+ * -------------------------------------------
+ * 2025. 11. 12.     byeonsungmun       최초 생성
+ */
+@RequiredArgsConstructor
+@Component
+public class BrandRepositoryImpl implements BrandRepository {
+
+    private final BrandJpaRepository jpaRepository;
+
+    @Override
+    public Optional<Brand> findById(Long id) {
+        return jpaRepository.findById(id);
+    }
+
+    @Override
+    public void save(Brand brand) {
+        jpaRepository.save(brand);
+    }
+}

apps/commerce-api/src/test/java/com/loopers/domain/brand/BrandTest.java

@@ -0,0 +1,42 @@
+package com.loopers.domain.brand;
+
+import com.loopers.support.error.CoreException;
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Nested;
+import org.junit.jupiter.api.Test;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
+
+/**
+ * packageName : com.loopers.domain.brand
+ * fileName     : BrandTest
+ * author      : byeonsungmun
+ * date        : 2025. 11. 14.
+ * description :
+ * ===========================================
+ * DATE         AUTHOR       NOTE
+ * -------------------------------------------
+ * 2025. 11. 14.     byeonsungmun       최초 생성
+ */
+class BrandTest {
+
+    @DisplayName("Brand 단위 테스트")
+    @Nested
+    class CreateBrandTest {
+
+        @Test
+        @DisplayName("브랜드 생성 성공")
+        void createBrandSuccess() {
+            Brand brand = Brand.create("Nike");
+            assertThat(brand.getName()).isEqualTo("Nike");
+        }
+
+        @Test
+        @DisplayName("브랜드 이름이 없으면 예외")
+        void createBrandFail() {
+            assertThatThrownBy(() -> Brand.create(""))
+                    .isInstanceOf(CoreException.class);
+        }
+    }
+}